Merge pull request #320 from scala-steward/update/sbt-site-1.4.0

Update sbt-site to 1.4.0

Author: zarthross

project/plugins.sbt

@@ -2,7 +2,7 @@ resolvers += "jgit-repo" at "http://download.eclipse.org/jgit/maven"
 
 addSbtPlugin("com.typesafe.sbt" % "sbt-ghpages" % "0.6.3")
 
-addSbtPlugin("com.typesafe.sbt" % "sbt-site" % "1.3.3")
+addSbtPlugin("com.typesafe.sbt" % "sbt-site" % "1.4.0")
 
 addSbtPlugin("com.eed3si9n" % "sbt-unidoc" % "0.4.2")